The present invention relates to extrusion billet taper quenching and more particularly, to water delivery systems and billet transportation systems used in such quenching.
In nonferrous extrusion, a billet is sequentially heated in a furnace, taper quenched, and extruded in a press. Taper quenching introduces a temperature gradient into at least a portion of the length of the billet. The temperature gradient produces more uniform extrusion temperatures and pressures as is desired in producing high quality extruded articles.
A variety of taper quenching systems and methods has been developed. One such system is illustrated in U.S. Pat. No. 5,027,634, issued Jul. 2, 1991, and entitled SOLUTIONIZING TAPER QUENCH. In that system, a billet is shuttled back and forth through vertical water dispensing rings which direct a shower of water onto the exterior of the cylindrical billet. Each water ring includes a plurality of holes about its circumference for directing the water onto the billet. Each water ring defines an opening in its upper portion enabling a billet pusher mechanism to pass therethrough.
While a marked improvement over prior quenching units, the water ring holes create difficulties. First, the high water pressure tends to enlarge the holes, thereby creating flow control difficulties. Second, the holes, which are quite small, can become plugged with contaminants within the water stream, further contributing to flow control difficulties. Third, the holes are predrilled for a single preselected flow of water only.
The opening in the ring also creates difficulties. Most notably, water is not discharged from the area of the ring opening. Accordingly, the cooling pattern is not uniform about the full circumference of the billet, creating temperature control difficulties.